Drive units are widely used in many applications, such as electric mowers and powered lift gates. The drive unit used in an electric mower generally comprises a motor and a gear reduction unit. The gear reduction unit generally emits great noise in high speed operating conditions. Such noise is often considered as noise pollution. In other applications involving lower operating speeds, the noise is not as great but may still be too loud where quiet operation is desired, such as in the drive units for powered lift gates in passenger vehicles.